[b1_ana] Fwd: Re: BCM accuracy

[J. P. Chen]

-------- Original Message --------
Subject: 	Re: BCM accuracy
Date: 	Mon, 6 May 2013 18:30:51 +0800
From: 	Pengjia <pzhu at jlab.org>
To: 	Jian-ping Chen <jpchen at jlab.org>, Alexandre Camsonne 
<camsonne at jlab.org>



Since T3 rate also depends on target type and momentum setting, I need 
to find a period that have stable momentum setting and  same target for 
more than 20hours(i don't know if it has or not,maybe I can try to look 
at the gep data, though it is at low current as 5~10nA), or I need to 
find a new way to check the stability other than T3.


Pengjia


On Mon, May 6, 2013 at 5:27 PM, Pengjia <zhupengjia at gmail.com 
<mailto:zhupengjia at gmail.com>> wrote:

    Hi JP,
    Sorry for late, I don't know the deadline is tonight before.
    I checked several production runs by using T3 count and bcm count
    saved in helicity ringbuffer(since there is more events saved in
    ringbuffer raw data(1 event recorded per 0.001s) than in normal
    sis3800 scaler(1 event recorded per 2s), also I checked from normal
    sis3800 scaler and got same result), the main idea is:
    1.calculate the charge(after calibration) rise,T3 count rise  per 1
    second(bcm count rise in 1 sec), time use fastclock
    2.get the ratio between T3 count rise and charge rise(total), fit it
    as charge=a+b*t3
    3.get the relationship between
    (charge_per_sec-(a*t3_per_sec))/charge_per_sec
    The result is:
    by using run from 4234 to 4249,  from 4/12/2012 14:24 to 4/12/2012
    18:50,
    the result can be shown in attachment, t3ps is t3 count per second,
    upps is calibrated upstream bcm charge per second, clk is from
    fastclock/103920, unit is second
    the stability in 5 hours can be reach as 0.75%, less than 1%,
    more data need to be replayed for study for more than 20hours.
    Is it what you want? Thanks!


    Pengjia

    On 05/06/2013 04:51 AM, Jian-ping Chen wrote:
>     Pengjia,
>
>     The deadline for submitting the proposal is 8 am Monday (US East
>     time),
>     Will need the inf on long-term (~20-24 hours) stability for the
>     BCM some hours
>     before the deadline. We have only a few hours left.let me know if
>     you have anything.
>
>     Thanks.
>
>     Jian-ping
>
>     On 5/4/2013 5:16 AM, Pengjia wrote:
>>     Hi JP, Alex,
>>     I will figure it out as soon as possible, Thanks!
>>
>>     Pengjia
>>
>>
>>     On Sat, May 4, 2013 at 5:56 AM, J. P. Chen <jpchen at jlab.org
>>     <mailto:jpchen at jlab.org>> wrote:
>>
>>         Hi, Pengjia and Alexandre,
>>
>>         I need information on BCM for 100 nA. Precision and stability.
>>         Also a question: do we reach 1% (statistics) in less than 1 s?
>>
>>         Thanks.
>>
>>         Jian-ping
>>
>>
>>         On 5/3/2013 5:36 PM, Alexandre Camsonne wrote:
>>>         I guess you could normalize by trigger rates too to correct
>>>         for beam fluctuations.
>>>
>>>         Alexandre
>>>
>>>
>>>         On Fri, May 3, 2013 at 5:19 PM, Alexandre Camsonne
>>>         <camsonne at jlab.org <mailto:camsonne at jlab.org>> wrote:
>>>
>>>             Hi Pengjia,
>>>
>>>             JP would need the accury to which we measure the charged=
>>>             at 50 nA.
>>>
>>>             I need to look back at the data
>>>
>>>             but I think we have several calibrations
>>>             with the calorimeter.
>>>
>>>             Could you make a plot of the stability
>>>             of the calibration constants ?
>>>
>>>             Also can you plot the width of the measured current ?
>>>
>>>             And give the resolution on the current we have :
>>>
>>>             sigma / mean.
>>>
>>>
>>>             Alexandre
>>>
>>>
>>
>>
>




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